1. Technical Field
The present invention relates to an electronic timepiece that receives signals transmitted from GPS satellites or other positioning information satellites.
2. Related Art
GPS satellites with known orbits around the Earth are used in the GPS system, which is a system for determining one's position, and each GPS satellite carries an atomic clock. Each GPS satellite therefore also keeps extremely precise time information (also referred to as the GPS time or satellite time).
Electronic timepieces that use time information contained in navigation data sent from GPS satellites to correct internal time information kept by a timekeeping means are known from the literature. See, for example, Japanese Unexamined Patent Appl. Pub. JP-A-2010-60456.
JP-A-2010-60456 describes an electronic timepiece that in the reception process that receives satellite signals from GPS satellites first searches for a GPS satellite from which a satellite signal can be received, and then receives satellite signals from the GPS satellite that was locked onto by the search.
Executing the process that receives satellite signals from GPS satellites while indoors, however, is difficult. So that the reception process is executed while outdoors, configurations that provide the electronic timepiece with an illuminance detection means and execute the reception process when a specific illuminance is detected by the illuminance detection means are also conceivable.
However, when the reception process is executed based on the illuminance detected by such an illuminance detection means, the frequency of the reception process may drop because the electronic timepiece is covered by clothing during the winter, for example, and the specific illuminance therefore cannot be detected. The time is therefore adjusted less frequently in this case, and the accuracy of the time displayed by the electronic timepiece may drop.
Configurations that automatically run the reception process at a preset regular time when the reception process based on the illuminance detection process has not been executed for a specific time are also conceivable.
However, the electronic timepiece could be located indoors at the set time, and locking onto a GPS satellite may not be possible even though the reception process is executed. If the reception process continues in this case, not only can the satellite signal not be received, the reception process simply increases power consumption.